Storage area networks (SANs) offer greater configuration flexibility, expandability and overall availability than their SCSI (Small Computer Systems Interface) counterparts. While many large organizations have adopted SANs, many smaller organizations continue to purchase SCSI systems. Among the reasons for the continued selection of SCSI over SAN solutions are the extensive cost and greater complexity of SAN installations and maintenance.
SAN implementations can be complex and costly because SANs generally require Fibre Channel networking through hubs or switches. Similar SCSI implementations, on the other hand, use generally well-settled technology that is typically inexpensive. Retailers of SAN systems and components face additional support challenges because of the more advanced nature of the technology and because of the flexibility of SANs combined with customer unfamiliarity. These potential customer support issues inevitably end up increasing the overall costs of SAN implementations.
Commonly available Fibre Channel switches come in eight (8), sixteen (16) and twenty-four (24) port configurations. Fibre Channel switches under development include versions having thirty-two (32) or more ports. For users requiring large-scale SAN implementations, these commonly available switches are suitable. However, for users wishing to implement basic failover cluster SAN configurations as well as simple storage and cluster consolidation, these commonly available switches constitute a significant investment and a potential barrier to widespread SAN implementation.
Some vendors have attempted to overcome the objections to SAN implementations by offering low-cost hubs for low-end configurations. Hubs generally offer ease of use and have cabling concerns as their only additional complexity. However, hubs do not generally offer the same performance and scalability that is offered by Fibre Channel switches. Consequently, users requiring more advanced networking configurations generally must replace their hub-based solutions.
Other propositions offered to overcome the objections to SAN implementations include reducing the number of ports available on switches, eliminating the redundant power available in many switch configurations and using port-zoning to divide a single switch into two halves to support redundant communication paths. While some advantages may be achieved through such propositions, no allowances for a reduction in complexity or an elimination of single points of failure have been made. Therefore, SAN implementations are still likely to take a backseat to simpler, cheaper SCSI solutions.